IET Lecture by Prof. Andy Sutton: Point to Point Microwave Radio Systems

Point to point microwave radio systems have been with us for more than eighty years, yet they rarely attract much attention in an era where fibre dominates network planning and satellite systems continue to develop at pace. At a recent IET Anglian Coastal Local Network event, Prof. Andy Sutton delivered an excellent lecture that brought these fixed radio links back into the spotlight. His talk explored the history, engineering and future of microwave and millimetre wave links, reminding us why they remain essential for transmission networks in the UK and around the world.

The story begins with the national microwave radio network of the 1970s, with the BT Tower at its centre. These early deployments supported long links across the country and laid the foundation for many of the design principles still used today. While the landscape has changed significantly, the fundamentals of fixed radio communication continue to be shaped by spectrum availability, propagation characteristics and careful engineering.

Microwave links depend on a wide range of bands, from the lower 6 GHz region through to 80 GHz E-band. The choice of frequency affects everything from link length to susceptibility to atmospheric absorption. As Andy explained, a link designer must consider not just free space path loss, but also Fresnel zone clearance, rainfall intensity and antenna characteristics. The slides included a worked example that showed the impact of frequency and distance on the radius of the Fresnel zone and highlighted the need for adequate clearance to maintain availability over time.

The talk moved on to modern access radio systems, where compact rooftop nodes and all-outdoor radios have become common. These systems rely on careful use of vertical and horizontal polarisations, often enabled through XPIC technology. XPIC allows separate data streams to coexist on the same frequency using orthogonal polarisations, effectively doubling link capacity when conditions allow. This is paired with adaptive coding and modulation, which enables the radio to shift modulation schemes according to link quality. The result is a more resilient and efficient link compared to older fixed-modulation systems.

Capacity planning is a balancing act that involves radio channel bandwidth, modulation choice and the number of aggregated carriers. Wider channels and higher order modulation support multi-gigabit throughput, although this introduces penalties in transmit power and receiver sensitivity. The trade-offs are central to radio design and determine the type of equipment used, whether through a separate indoor and outdoor unit or an integrated all-outdoor system.

Andy also covered the practical elements of radio link planning, such as antenna selection, path profiling, waveguide losses and typical link budget calculations. A link planning example using a 32 GHz radio demonstrated the relationship between transmit power, antenna gain, free space loss and fade margin for a target availability of 99.99 percent. The discussion tied together the theoretical foundations with real-world engineering and illustrated how access radios are designed for street-level backhaul scenarios.

The lecture then moved to millimetre wave systems, particularly E-band radios that operate around 70 and 80 GHz. These links offer enormous capacity over shorter distances and are increasingly used for dense urban backhaul and enterprise connectivity. The slides included examples of network topologies showing how microwave and fibre can be combined to meet different deployment objectives.

A substantial part of the presentation focused on trunk or core microwave radio systems. These high-capacity, high-availability links support long distances and historically formed the backbone of national networks. Although demand for trunk links has reduced as fibre has spread, they still exist in challenging environments. In the UK, many trunk links remain operational in Scotland and island regions where terrain and geography limit fibre deployment. The lecture covered branching networks, duplexers, waveguide installations and space diversity techniques, all of which contribute to the reliability of long-haul links.

Looking ahead, research continues into new frequency bands, wider channels, higher modulation schemes and improved radio hardware. These advances will support even greater capacities, with millimetre wave links expected to reach 100 Gbps over short distances. Microwave radio may no longer be the headline technology it once was, but the field continues to push boundaries and remains an essential part of modern communication networks.

Andy’s lecture was a comprehensive tour of the past, present and future of point to point microwave systems. For anyone working in transmission, mobile networks or wireless engineering, it served as a valuable reminder of the depth of innovation in this area and its continued relevance in the broader ecosystem.

If you would like to explore the material in more detail, the slides from the event are available here and the video can be seen here. Both are well worth a look.

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• Connectivity Technology Blog - 5G Demystified; the What, When and Where by Prof. Andy Sutton, BT
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AIoT and A-IoT

Our industry loves acronyms. In fact, sometimes it feels as if half our job is simply keeping up with them, while the other half is explaining them to everyone else. A recent example I saw referenced D2D for satellites, but expanded it as Device to Device instead of Direct to Device. Today, two similar acronyms are gaining momentum and are likely to become far more mainstream: AIoT and A-IoT.

Artificial Intelligence (AI) and the Internet of Things (IoT) are two of the key technological pillars of the modern digital world. IoT connects billions of devices, from sensors and cameras to industrial machinery, all producing vast amounts of useful data. AI enables these devices and systems to learn from this data, recognise patterns, predict outcomes, and act autonomously.

When these technologies come together, we get the Artificial Intelligence of Things, or AIoT. In simple terms, AIoT allows connected devices to analyse the data they generate and make decisions without always relying on central systems.

The intelligence in AIoT can sit in different places. Cloud based AI offers extensive processing power and the ability to leverage wider datasets. Edge AI processes data closer to where it is generated, enabling faster and more context aware decision making while reducing bandwidth use and protecting data privacy. Increasingly, lightweight machine learning models allow intelligence directly on devices themselves, enabling instant reactions without constant network access. This evolution transforms IoT devices from passive data collectors into proactive decision makers.

The benefits are significant. AIoT increases automation, improves efficiency, enhances reliability, and enables predictive maintenance, energy optimisation, autonomous navigation, and smarter logistics. It also supports sustainability initiatives, for instance by improving energy and water use monitoring or enabling more intelligent control of municipal utilities. In short, AIoT forms a key part of the digital transformation strategies emerging across industries.

To get a better sense of how AIoT could shape our everyday lives, I have embedded a couple of older Ericsson videos below that imagine a future where intelligence is seamlessly built into everything.

For anyone interested in going deeper into this topic, Transforma Insights and Supermicro have good explainers. While 3GPP continues to work on AI, ML and IoT, AIoT as a concept is largely implementation driven rather than a standardised feature in itself.

In contrast, 3GPP is actively defining a different acronym: A-IoT, short for Ambient IoT.

Ambient IoT represents a major shift in connected device design. Instead of relying on batteries or frequent charging, Ambient IoT devices operate using energy harvested from their surroundings. This can include radio signals, light, heat, or motion. The technology supports both passive operation, where devices backscatter incoming RF signals, and active operation, where they harvest enough power to generate and transmit signals independently.

Unlike traditional IoT devices, Ambient IoT units are extremely low power, low cost, and very simple in design. They have a shorter range and lower data throughput than conventional wireless technologies, but they excel in scenarios where massive numbers of tiny, battery-free sensors can be deployed and left to operate with minimal maintenance.

This makes Ambient IoT well suited to applications such as environmental sensing, supply chain tracking, inventory monitoring, smart agriculture, and intelligent labelling. It also opens opportunities in consumer environments, from smart packaging to indoor positioning. With the right network support, these devices can operate indefinitely, enabling sustainable, large-scale sensing networks.

Ambient IoT is already included in 5G Advanced Release 19. For those interested in learning more, 3GPP has a detailed overview, Oppo has produced an excellent white paper, and LG Uplus has published a forward looking document exploring Ambient IoT in the context of 6G.

Both AIoT and Ambient IoT represent the next phase of connected intelligence. AIoT pushes computation and decision making closer to where data originates, while Ambient IoT removes power barriers and enables pervasive, maintenance-free connectivity. Together, they will support systems that are scalable, energy efficient and context aware.

As these technologies mature, we can expect a world where devices are not only always connected, but also constantly learning, adapting, and operating independently with minimal energy demands. The future of connectivity lies in this balance between intelligence and efficiency, and both AIoT and Ambient IoT will play a crucial role in shaping it.

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